ObamaCare's individual mandate
Under the Constitution, Congress has the authority "to regulate commerce with foreign nations, and among the several states, and with the Indian tribes." You'll notice that commercial activities by individuals is not on that list, so there is no specific constitutional authority for the federal government to mandate that a private citizen engage in commerce. Furthermore, the Tenth Amendment sends powers not specifically delegated to the federal government back to the states. It should be fairly obvious that ObamaCare's individual mandate is unconstitutional.
Yes, but the government mandates that we have automobile insurance, so is that not the same thing? No, it is not. First, auto insurance mandates are state mandates, not federal mandates. The states are given wide latitude under the Constitution to govern themselves in a way the federal government cannot. Second, the auto insurance mandate is not a universal mandate. If you do not own an automobile you do not have to purchase auto insurance. Third, auto insurance that is required is generally liability insurance, to cover the cost to other drivers in the case of an accident.
Democrats such as Rachel Maddow love to bring up the fact that some Republicans used to support the individual mandate. This is a common political tactic that produces heat but very little light. The fact that some Republicans used to support the mandate (even a federal mandate) does not address whether or not the mandate is good policy. It is an ad hominem logical fallacy meant to discredit one's political opponent as a hypocrite instead of honestly examining the policy and legal foundations for the arguments against the mandate.
It is understandable why some misguided Republicans and conservatives (which are not the same, though there is overlap) would have supported the mandate in the past. After all, a common belief among conservatives is that individual responsibility is critical, and requiring people to purchase a policy eliminates "free riders" that use emergency rooms and then do not pay. But the problem is that this is a dramatic expansion of federal power and sets a dangerous precedent for future expansions of federal power - not to mention the fact that it is plainly unconstitutional.
The problem with ObamaCare (as I said a couple years ago) is that it does not address one of the fundamental problems with our health care system - the health insurance industry itself. Insuring against catastrophic illness or injury is one thing, and is a way to spread risk across a large number of people for an affordable price to each individual. But health insurance has morphed more and more into health care, and that distorts the health care market.
When people are paying directly for their health care (especially routine doctor visits and such) they have an incentive to seek the best service for the best price - much like shopping for groceries or clothing. When health insurance routinely covers even routine medical care, that incentive is removed. It is a bad idea to have the consumer insulated from the cost of the product or service he is purchasing. I am convinced that this is one of the reasons health care costs have risen so sharply - much the same as student loans have distorted the market for college education.
What we need is not a top-down system where the federal government controls the health care system. We need reforms that will bring more market forces into the health care market.